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Re: Reading the Mill wiki: comments and a concern

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On 12/12/2014 11:46 AM, peterfirefly@gmail.com wrote:
> On Friday, December 12, 2014 8:31:36 PM UTC+1, Ivan Godard wrote:

>>    If you can wade through the "Prediction" talk, you will find there how
>> the Mill self-tuning prediction works. Beyond that, we have put a lot of
>> effort into making the Mill ISA optimization-proof. When code can be
>> optimized it means that the architecture design was lacking IMO, YMMV.
>
> Inlining and data layout (say, structure splitting)?
> Which conditional code to put far away (because it is rarely run) and which to put right next the code for the conditional?
>
> -Peter
>

I was only addressing things that profiling might help with. Inlining 
(done in the specializer on the Mill) becomes rather unimportant when 
call overhead has been reduced to the trivial: one op, one cycle on a 
Mill. We expect (no numbers yet, patience) that the biggest impact will 
be on internal fragmentation in the iCache and other second-order effects.

I've never seen a case where the benefit of structure splitting is 
profile dependent. Please explain a use-case.

I'm not saying that all optimization is useless. But (to take an 
especially egregious example) the optimization involved in address-mode 
instruction selection on a VAX says more about the VAX architectural 
design than about the cleverness of the VAX compiler writers.

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Reading the Mill wiki: comments and a concern jgd@cix.co.uk (John Dallman) - 2014-12-12 19:15 +0000
  Re: Reading the Mill wiki: comments and a concern Ivan Godard <ivan@ootbcomp.com> - 2014-12-12 11:31 -0800
    Re: Reading the Mill wiki: comments and a concern peterfirefly@gmail.com - 2014-12-12 11:46 -0800
      Re: Reading the Mill wiki: comments and a concern Ivan Godard <ivan@ootbcomp.com> - 2014-12-12 12:06 -0800
        Re: Reading the Mill wiki: comments and a concern peterfirefly@gmail.com - 2014-12-12 13:37 -0800
          Re: Reading the Mill wiki: comments and a concern Ivan Godard <ivan@ootbcomp.com> - 2014-12-12 16:50 -0800
    Re: Reading the Mill wiki: comments and a concern jgd@cix.co.uk (John Dallman) - 2014-12-12 20:24 +0000
      Re: Reading the Mill wiki: comments and a concern Ivan Godard <ivan@ootbcomp.com> - 2014-12-12 12:35 -0800
        Re: Reading the Mill wiki: comments and a concern Quadibloc <jsavard@ecn.ab.ca> - 2014-12-12 15:03 -0800
          Re: Reading the Mill wiki: comments and a concern Ivan Godard <ivan@ootbcomp.com> - 2014-12-12 17:01 -0800
    Re: Reading the Mill wiki: comments and a concern Quadibloc <jsavard@ecn.ab.ca> - 2014-12-12 14:54 -0800
      Re: Reading the Mill wiki: comments and a concern Ivan Godard <ivan@ootbcomp.com> - 2014-12-12 17:11 -0800
        Re: Reading the Mill wiki: comments and a concern Melzzzzz <mel@zzzzz.com> - 2014-12-13 04:36 +0100
          Re: Reading the Mill wiki: comments and a concern Ivan Godard <ivan@ootbcomp.com> - 2014-12-12 19:59 -0800

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